This project proposes to exploit established animal models of chronic interstitial pneumonitis and pulmonary fibrosis to elucidate pathogenetic mechanisms of relevance to related human diseases. A BCG model of granulomatous interstitial pneumonitis will be used primarily to study clearance mechanisms and immunologic requirements which result in lung injury. A paraquat model will be used primarily to study biochemical (proteinase, collagenase) accompaniments of pulmonary fibrogenesis and healing. The two models will form a complementary pair in studying immunological and biological accompaniments of pulmonary inflammatory response and fibrogenesis. The proposed studies of these models are expected to help clarify basic mechanisms of inflammation, healing and scarring in human lung diseases.